基于扩展有限元模型的动态应力强度因子计算

为准确计算基于扩展有限元法（XFEM）的裂纹扩展模型中的应力强度因子，在ABAQUS软件中建立中心裂纹平板和三点弯曲的XFEM模型，采用相互作用积分法，通过用户子程序接口分别实现了Ⅰ型、Ⅱ型断裂模式下裂纹扩展过程中应力强度因子的计算；研究了网格密度与积分半径对XFEM模型应力强度因子计算精度的影响规律，研究结果表明：当网格密度因子为0.012~0.016、相对积分半径为3时，应力强度因子收敛至稳定值，计算误差不超过3%。利用所提方法与程序计算了单边带孔疲劳裂纹扩展试样的动态应力强度因子，试验结果表明：基于Paris理论预测的剩余寿命与疲劳试验结果误差为5.3%，进一步验证了所提方法与程序的正确性。

Calculation of Dynamic Stress Intensity Factors Based on XFEM Model

In order to accurately calculate the stress intensity factors in the crack propagation model based on XFEM, the XFEM model of central crack plate and three-point bending were established in ABAQUS software. The stress intensity factors in the crack propagation processes were realized under mode Ⅰ and Ⅱ fracture modes respectively by using interactive integration method and user subroutine interface. The influences of mesh density and integral radius on the accuracy of stress intensity factor calculation for XFEM were studied. The research results show that when the mesh density factor is as 0.012~0.016 and the relative integral radius is as 3, the stress intensity factors converge to a stable value and the calculation errors are less than 3%. The dynamic stress intensity factors of fatigue crack growth specimens with single side hole were calculated by using the proposed method and programs. The testing results show that the errors between the residual life predicted by Paris theory and the fatigue test results are as 5.3%, which further verifies the correctness of the proposed method and programs.